Linux Mint Japan, the official local community in Japan, have translated official user guides. They are capable of the latest Linux Mint version (Qiana) .
I would like to upload these files on the official web site.

Took a bit longer to get the time for it, with all the work ongoing for 17.1, but the files are now online on http://www.linuxmint.com/documentation.php
Again, thanks very much to the local community for doing the translation!